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01 Record

CVE-2026-40355

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An

MediumPUBLISHEDCNA: mitre
CNA base score5.9 CVSS v3.xCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
View raw JSON

02 Description

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.64% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 50.6% of scored records. A rank, not a probability.
NVD base score
7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-10-26.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-04-28 00:00Z6 MO AGO
Last updated
2026-10-15 01:18Z14 DAYS AGO
Reserved
2026-04-11
Assigning CNA
mitre
Record state
PUBLISHED
Severity
Medium (CVSS 5.9)
CNA CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
  • CWE-476NULL Pointer DereferenceBase
Data version
5.2
Document digest
50d2aede5a5ae096dbda93c5e1a714e7ca1050a6a7446fddf436f121e48109b7

05 Affected products

VendorProductVersionsPlatforms
MITKerberos 51.18 to < 1.22.3—

06 References

07 Fixed in

AlmaLinux 8

  • krb5-devel
    Fixed in 1.18.2-34.el8_10
  • krb5-libs
    Fixed in 1.18.2-34.el8_10
  • krb5-pkinit
    Fixed in 1.18.2-34.el8_10
  • krb5-server
    Fixed in 1.18.2-34.el8_10
  • krb5-server-ldap
    Fixed in 1.18.2-34.el8_10
  • krb5-workstation
    Fixed in 1.18.2-34.el8_10
  • libkadm5
    Fixed in 1.18.2-34.el8_10

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 9

  • krb5-devel
    Fixed in 1.21.1-10.el9_8
  • krb5-libs
    Fixed in 1.21.1-10.el9_8
  • krb5-pkinit
    Fixed in 1.21.1-10.el9_8
  • krb5-server
    Fixed in 1.21.1-10.el9_8
  • krb5-server-ldap
    Fixed in 1.21.1-10.el9_8
  • krb5-workstation
    Fixed in 1.21.1-10.el9_8
  • krb5-xrealmauthz
    Fixed in 1.21.1-10.el9_8
  • libkadm5
    Fixed in 1.21.1-10.el9_8

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 10

  • krb5-devel
    Fixed in 1.21.3-10.el10_2
  • krb5-libs
    Fixed in 1.21.3-10.el10_2
  • krb5-pkinit
    Fixed in 1.21.3-10.el10_2
  • krb5-server
    Fixed in 1.21.3-10.el10_2
  • krb5-server-ldap
    Fixed in 1.21.3-10.el10_2
  • krb5-workstation
    Fixed in 1.21.3-10.el10_2
  • krb5-xrealmauthz
    Fixed in 1.21.3-10.el10_2
  • libkadm5
    Fixed in 1.21.3-10.el10_2

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 8

  • krb5-devel
    Fixed in 1.18.2-34.el8_10
  • krb5-libs
    Fixed in 1.18.2-34.el8_10
  • krb5-pkinit
    Fixed in 1.18.2-34.el8_10
  • krb5-server
    Fixed in 1.18.2-34.el8_10
  • krb5-server-ldap
    Fixed in 1.18.2-34.el8_10
  • krb5-workstation
    Fixed in 1.18.2-34.el8_10
  • libkadm5
    Fixed in 1.18.2-34.el8_10

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • krb5-devel
    Fixed in 1.21.1-10.el9_8
  • krb5-libs
    Fixed in 1.21.1-10.el9_8
  • krb5-pkinit
    Fixed in 1.21.1-10.el9_8
  • krb5-server
    Fixed in 1.21.1-10.el9_8
  • krb5-server-ldap
    Fixed in 1.21.1-10.el9_8
  • krb5-workstation
    Fixed in 1.21.1-10.el9_8
  • krb5-xrealmauthz
    Fixed in 1.21.1-10.el9_8
  • libkadm5
    Fixed in 1.21.1-10.el9_8

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 10

  • krb5-devel
    Fixed in 1.21.3-10.el10_2
  • krb5-libs
    Fixed in 1.21.3-10.el10_2
  • krb5-pkinit
    Fixed in 1.21.3-10.el10_2
  • krb5-server
    Fixed in 1.21.3-10.el10_2
  • krb5-server-ldap
    Fixed in 1.21.3-10.el10_2
  • krb5-workstation
    Fixed in 1.21.3-10.el10_2
  • krb5-xrealmauthz
    Fixed in 1.21.3-10.el10_2
  • libkadm5
    Fixed in 1.21.3-10.el10_2

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • krb5
    Fixed in 1.20.1-2+deb12u5

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • krb5
    Fixed in 1.21.3-5+deb13u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • krb5
    Fixed in 1.22.1-2.1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • krb5
    Fixed in 1.19.2-2ubuntu0.8

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 24.04 LTS

  • krb5
    Fixed in 1.20.1-6ubuntu2.7

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 25.10

  • krb5
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

  • krb5
    Fixed in 1.22.1-2ubuntu4.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.